1. Field of the Invention
The invention relates to a data management method, more particularly to a data management method for a storage device that includes multiple types of flash memories.
2. Description of the Related Art
A solid-state drive (SSD), which utilizes the flash memory technology, has the advantages of having fast access speed, low power consumption, lightweight, etc., when compared to a conventional hard disk. Currently, it is common for the flash memory to be used in USB drives, memory cards, mobile phones, notebook computers, etc.
At present, a flash memory used by a solid-state drive utilizes a floating gate transistor for data storage. There are single-level cell (SLC) type flash memories and multi-level cell (MLC) type flash memories, which differ in storage capacity of each cell in the flash memory. The SLC type flash memory stores one bit of data in each memory cell. On the other hand, the MLC type flash memory is currently capable of storing two bits of information in each memory cell. The MLC type flash memory, as compared to the SLC type flash memory, has the advantages of being cheaper and having a greater storage capacity. On the other hand, the SLC type flash memory, as compared to the MLC type flash memory, has higher stability, faster access speed (approximately 2 to 3 times of that of the MLC type flash memory), and a longer service life (i.e., permitting a total number of times that data has been erased from each memory cell that is approximately 10 times that of the MLC type flash memory).
In order to possess the advantages of both the faster access speed and longer service life of the SLC type flash memory and the lower cost and larger storage capacity of the MLC type flash memory, a hybrid solid-state drive that incorporates both the SLC type flash memory and the MLC type flash memory has been developed. However, current data management techniques, such as those disclosed in Taiwanese Patent No. I293729 and Taiwanese Patent Publication No. 200705180, do not take into consideration the differences in characteristics between different types of flash memories in a single storage device. Therefore, how to effectively manage data in a storage device that includes different types of flash memories so as to truly utilize the advantages of the different types of flash memories is a very important subject in the relevant art.